🔐 Secure Messaging System

This project is a secure client-server messaging system written in Python. It uses a mix of RSA and AES encryption, digital signatures, and timestamp validation to guarantee:

• Confidentiality
• Authenticity
• Replay protection
• Offline message delivery

✨ Features

• 📱 Client registration via two-step verification (code + public key)
• 🔑 Secure key exchange (RSA for handshake, AES for messaging)
• 💬 End-to-end encrypted messaging with digital signatures
• 🕓 Timestamp validation to avoid replay attacks
• 📥 Offline message queuing and delivery upon reconnect

📁 Structure

main.py
├── Server.py
├── ConnectionManager.py
├── Client.py
├── utils/
│   ├── AESEncryption.py
│   ├── RSAManagement.py
│   ├── NumericSignatureAndTimeStamp.py
│   ├── communicationFunctions.py
│   ├── getRSAKeys.py
│   └── randomPhoneNumber.py

🚀 How to Run

Start the Server

python main.py server

Start a Client

python main.py client

Simulate Two Clients Communicating

python main.py 2clients

🛡️ Technologies Used

• RSA 2048-bit, AES 256-bit
• Python sockets & threading
• Cryptography library
• JSON & UTC timestamps

⬇️ Download

Download ZIP of the full project →

“Don't listen to the person who has all the answers. Listen to the person who has the questions.”